1. Field of the Invention
The present invention relates generally to facilitating communications between a cellular telephone and a multi-handset cordless telephone system and, more particularly, to a system for routing messages between a cellular telephone and one or more handsets in a multi-handset cordless telephone system.
2. Background of the Invention
Many users (e.g., consumers and business persons) possess both a landline telephone and a cellular telephone. While telephone infrastructure varies from country to country (and indeed, this invention is not limited to any particular country), the United States infrastructure provides a useful starting point for purposes of this description. In the United States, a landline telephone can be a cordless or corded telephone that is coupled to a central office (“CO”) of a local exchange carrier (“LEC”) such as a Regional Bell Operating Company (“RBOC”), a competitive local exchange carrier (“CLEC”), and so on, and is commonly referred to as a PSTN-based telephone system. Cordless telephones have no cord between the handset and base. Instead, the handset and base each have a radio transmitter, receiver, and antenna to allow communication between the handset and base. Typically, the handset includes a rechargeable battery, and the base is powered by current from an alternating current (“AC”) outlet (e.g., of a house or office). In a residential environment, the base is typically coupled to the CO via one or more wires, such as an RJ-11 wire that couples the base to an RJ-11 jack on a wall. The RJ-11 jack is typically coupled to the CO via a twisted-pair wire.
As used to describe the background and embodiments of the present invention, the term “coupled” encompasses a direct connection, an indirect connection, or a combination thereof. Two devices that are coupled can engage in direct communication, in indirect communication, or a combination thereof. Moreover, two devices that are coupled need not be in continuous communication, but can be in communication typically, periodically, intermittently, sporadically, occasionally, and so on. Further, the term “communication” is not limited to direct communication, but also includes indirect communication.
The range of effective communications between a handset and base can be from about 10 feet to several miles depending on factors such as product design, operating radio frequency, environmental conditions, and legal restrictions (e.g., laws and regulations). Examples of known operating radio frequencies for cordless telephone communications in the United States include 900 Megahertz (“MHz”), 2.4 Gigahertz (“GHz”), 5.8 GHz, a combination thereof, and so on.
An example of a cellular telephone is a handheld cellular radio transceiver (transmitter/receiver) that operates in a cellular service area composed of a plurality of cells. Each cell is populated with one or more low-powered radio transceivers that communicate with the cellular telephones in or about the cell. Adjoining cells typically operate at different radio frequencies. Each cell's radio transceiver is coupled to a Mobile Telephone Switching Office (“MTSO”) that can monitor the movement, if any, of the cellular telephone (e.g., by determining or receiving signal strength indicators corresponding to the cellular telephone) through the cell such that, at the proper time, the cellular telephone can be handed-off from a current cell to a next cell. Examples of cellular telephone systems include Personal Communications Service (“PCS”) systems, Global System for Mobile Communications (“GSM”) systems, Code Division Multiple Access (“CDMA”) systems, Time Division Multiple Access (“TDMA”) systems, analog and/or digital Advanced Mobile Phone Service (“AMPS”) systems, and so on. Cellular telephone systems in the United States operate at or around 1900 MHz (e.g., GSM 1900 systems, Digital AMPS, and CDMA 1900 systems), in the 800-900 MHz range (e.g., analog AMPS), and so on.
Many users own both a landline telephone and a cellular telephone. There is a strong user desire to use cellular telephone services from the comfort of the home landline telephone. Other users want to use the handset of their cordless telephone to communicate with others via the wireless network of the cellular telephone.
With the rise of the use of short-range radio frequency communications, such as the Bluetooth specifications, cellular telephones have been configured to communicate with PSTN (public switched telephone network) telephone hardware, and vice versa, in order to establish a local voice connection between the two systems. One such system has been described in U.S. Patent Application Publication No. US2004/0132500, filed Jul. 17, 2003, now U.S. Pat. No. 7,363,045, issued Apr. 22, 2008, which is incorporated herein by reference in its entirety.
In establishing a voice link between a cellular telephone and a cordless telephone system, a cordless telephone system is configured to effectively support a second telephone line by using the cellular phone link as a replacement for a traditional PSTN connection. Using the cellular phone connection as this “second line” requires an interface between the cellular phone and the cordless telephone system. Short-range radio frequency specifications, such as Bluetooth, have been used to provide this connection. These conventional systems, however, have limited capabilities since they only enable simple voice calling (e.g., making and receiving a call) and limited data transfer. The advantage of the conventional cellular-to-cordless interconnection is that it allows multiple cordless handsets throughout a home to make and receive calls made to the cellular handset. This reduces the need for a cellular phone to be carried throughout the house, reduces cellular radiation because lower power cordless phones are used, and provides the convenience of a “second line” without the need to add an actual second PSTN line.
Several means for providing messaging services are currently provided. One system is simply a personal computer running messaging software. This device is expensive and must always be on to support reliable messaging. In addition, the personal computer must be connected to an external network (e.g., the internet) using a suitable connection (e.g., broadband, wireless, or dial-up). This external network connection also adds additional monthly subscriber costs.
Another conventional system uses WiFi-enabled voice/messaging terminals. These terminals use “Voice over IP” (VoIP) to provide voice services over a wireless internet link. Since these services are internet-based, they can also provide messaging applications. One disadvantage of this system is cost. The terminals use 802.11 technology, which uses more expensive components over cordless and has a greater power consumption than cordless. Another disadvantage of this system is that, although data applications such as messaging are fairly reliable, VoIP over WiFi is still very unreliable. Thus, the system provides a good messaging device but a poor telephony device. WiFi terminals require a WiFi router at an additional cost and also an external network connection adding further subscriber costs.
Another conventional system is PC-assisted messaging terminals with voice capabilities. These devices support cordless telephony with a USB or Ethernet connection to an external PC that is responsible for providing the messaging support. Although more cost effective than the WiFi-enabled terminal, they require an active (powered) personal computer plus the external network connection.